1. Technical Field
This application claims the benefit of Japanese Patent Application No. 2004-309132, filed Oct. 25, 2004 and Japanese Patent Application No. 2005-227566, Filed Aug. 5, 2005. The entire disclosure of the prior applications are hereby incorporated by reference herein in their entirety.
The present invention relates to a technology in which an electro-optical material is used to display images.
2. Related Art
An electro-optical device, which uses an electro-optical material, such as liquid crystal or the like, to display images, has been widely used. As a method of driving such an electro-optical device, for example, in JP-A-2003-255904, a driving method has been disclosed in which voltage signals (hereinafter, referred to as gray-scale signals) for defining gray-scale levels of a plurality of pixels in a time-division manner are output to be divided for the respective pixels. FIG. 11 is a circuit diagram showing the configuration of a part in respects to driving data lines in an electro-optical device which uses such a method. FIG. 12 is a timing chart showing the operation of the electro-optical device. As shown in FIG. 11, a plurality of data lines 13 are divided into groups G (G1, G2, . . . ) each group having three data lines 13, and the three data lines 13 belonging to each group G are connected to a common image signal line 53 via switching elements 151, such as thin film transistor (TFT) elements or the like. The gate electrodes of the respective switching elements 151 belonging to one of the groups G are connected to different sampling signal lines 51. To the sampling signal lines 51, as shown in FIG. 12, sampling signals S1 to S3, which sequentially become active levels in different periods (hereinafter, referred to as ‘data output periods’) Td, are supplied.
To each image signal line 53, the gray-scale signal dj (where j is a natural number) for defining the gray-scale levels of the respective pixels connected to the three data lines 13 belonging to one of the groups G is supplied. For example, as shown in FIG. 13, it is assumed that the pixels connected to the first and second data lines 13 of the three data lines 13 belonging to the group G1 are caused to display halftone (gray), while the pixels connected to the third data line 13 are caused to display black. In this case, as shown in FIG. 12, the gray-scale signal d1 supplied to the image signal line 53 of the group G1 has a voltage Vg corresponding to halftone in the first and second data output periods Td of the horizontal scanning period (1H), and has a voltage Vb corresponding to black in the third data output period Td. With this configuration, the three switching elements 151 corresponding to each group G are sequentially turned on in the respective data output periods Td by the sampling signals S1 to S3, and, a voltage of the gray-scale signal d1 at that time is output and correspondingly applied to the data lines 13 as data signals Xa1, Xb1, and Xc1.
However, in this configuration, when the pixels connected to a specified data line 13 belonging to each group G (for example, in the configuration of FIG. 1, the third data line 13 of each group G) and the pixels connected to other data lines 13 of the corresponding group G have different gray-scale levels from each other, the gray-scale levels of the pixels corresponding to the respective data lines 13 of the latter may have the gray-scale levels different from the original gray-scale levels. For example, in an electro-optical device which uses a normally white mode, it is assumed that the pixels of the third column of the group G1 (that is, one black vertical line is displayed with a gray background) are used. In this case, as shown in FIG. 13, the gray-scale levels of the respective pixels of the third column belonging to the group G1 are targeted to become black, and the gray-scale level of each of the pixels of the group G2 becomes expected halftone. However, each of the pixels of the first and second columns belonging to the group G1, which originally becomes halftone, is darker than halftone, unlike other pixels of the group G2. This difference between the gray-scale levels may be perceived by a user as display irregularity.